The present invention relates to a transmission control apparatus and method of an earth station for satellite communication in a satellite communication system including a plurality of earth stations on the earth to conduct communications through a transmission channel shared therebetween and the earth stations conduct communications with each other via a satellite repeater, and in particular, to a transmission control method of a earth station for satellite communication suitable for a satellite news gathering (SNG) system in which materials of broadcast video news are transmitted via the satellite communication.